Sensitivity analyses
A number of sensitivity analyses were performed to check for possible bias of the results. These analyses showed that age, gender, EDSS at baseline, relapse within one month before initiation of natalizumab (Y/N), number of relapses within 6 months prior initiation of natalizumab, time from the last relapse to the first natalizumab infusion, and previous MS therapy (e.g. IFN beta) within one month were not associated with primary endpoint of this study. Multivariate regression model showed that patients having higher FSMC total score at baseline were more likely to improve after 12 months of natalizumab treatment (Odds Ratio (OR) = 1.084, 95% CI [1.01, 1.16], p = 0.02), and patients having lower depression score at baseline were more likely to improve after 12 months of treatment (OR = 0.905, 95% CI [0.84, 0.98], p = 0.01). However, sensitivity analysis adjusted for fatigue and depression baseline scores showed consistent results as previous findings, with a mean reduction of 9.5 (95% CI −11.9, −7.1). Last observation carried forward (LOCF) analyzing the FSMC showed consistent results (data not shown).